1. Field of the Invention.
This invention relates generally to fluid pumps, and more specifically to pumps used in wells.
2. Description of the Prior Art.
Many bladder or diaphram pumps have been designed in the past. The most pertinent to the present invention are M. J. Eull, U.S. Pat. No. 3,427,987; P. L. Scott, U.S. Pat No. 1,965,006; and W. E. Ellis, U.S. Pat. No. 1,546,973. Eull uses air pressure to collapse a bladder; while Scott uses a yoke. Ellis is somewhat different in principle using a bellows arrangement. In a down-the-well situation, Eull must have long lines which means that a lot of compressed air must be pumped. Scott is difficult to use because of the space constraints in well casings. Complexity in a down-the-well situation is very undesireable because it leads to maintenance problems.